This peptide is found only in the Archaea. It is paralogous to the gatB-encoded subunit of Glu-tRNA(Gln) amidotransferase. The GatABC system operates in many bacteria to convert Glu-tRNA(Gln) into Gln-tRNA(Gln). However, the homologous system in archaea instead converts Asp-tRNA(Asn) to Asn-tRNA(Asn). Glu-tRNA(Gln) is converted to Gln-tRNA(Gln) by a heterodimeric amidotransferase of GatE (this protein) and GatD.
The Archaea have an Asp-tRNA(Asn) amidotransferase instead of an Asp--tRNA ligase, but the genes have not been identified. It is likely that this protein replaces gatB in Asp-tRNA(Asn) amidotransferase but that both enzymes share gatA.